The Upper Respiratory System includes the Ears, Nose, Sinuses, Mouth, Throat, Vocal Cords (in the Larynx), and Trachea. Specialists in this are called “Otorhinolaryngologists,” which simply means “Ear-Nose-Throat Specialist” in Greek. In English, we commonly say “ENT Specialists.”
Figure 1 shows a basic diagram of where air travels, highlighted in red (the “Upper Airway”). Inhaled air enters through either the Nose or the Mouth. Those passageways join in the back of the throat (“pharynx” = “throat” in Greek; “pharyngitis” means “sore throat”). Air then continues on down into the Trachea, the “breathing tube” in our neck that leads to the Lungs. Air breathed out of the Lungs comes up the Trachea, through the Larynx (“voice box”) with its Vocal Cords (which let us speak, if we want), before being exhaled through the Mouth or Nose.
Since we also use our Mouths to eat, swallowing directs food down the Esophagus, which leads to the Stomach. The small flap called the Epiglottis automatically covers the Larynx as we swallow, so food doesn’t enter the Trachea or Lungs (“down the wrong pipe”). You can imagine a hunk of food going the wrong way if we eat too fast, which is why some people occasionally choke to death.
Some structures aren’t shown in Figure 1, like the Ears & Sinuses. We don’t use them to breathe, but they’re connected to the Upper Airway, so are part of the Upper Respiratory System. Logically, ENT specialists deal with them as well. Figure 1 shows the “Opening to the Eustachian Tube,” which runs from the back of the nose to the middle ear, where it maintains a normal pressure (see Ear – Anatomy).
Figure 2 shows our Sinuses, which are empty holes in our skull bones. Otherwise, our heads would be way too heavy for us to carry around. Tiny openings (not shown) connect each Sinus to the Nasal Passage, which means that germs from the Nose can infect the Sinuses. In very rare cases if the infection is very severe, especially in the Frontal or Sphenoid Sinuses, the germs can destroy bone & spread straight back to the Brain.
The following are the most common conditions to affect the Upper Respiratory System. Infections can occur in the Sinuses (sinusitis), Nose (rhinitis), Mouth (stomatitis), Throat (pharyngitis), Tonsils (tonsillitis), Larynx (laryngitis) and Trachea (tracheitis). Most such infections are caused by viruses, which can’t be treated by antibiotics, as opposed to less frequent though still common bacteria (see Differences Among Germs). Sometimes it can be hard to tell the difference, although rhinitis (the common cold) and stomatitis are always viral. Tooth infections are always bacterial, as are the very rare but likewise dangerous deep mouth and throat abscesses, and epiglottitis.
The main Upper Respiratory Tract disease not caused by germs is allergic rhinitis, commonly referred to as “allergies.” Symptoms are usually runny nose, congestion, and sneezing, but can also cause ear pain or pressure due to eustachian tube dysfunction. The latter also commonly bothers us during airplane take-offs & landings. Allergic Rhinitis (“allergies”) are much more common than sinus infections; the majority of people who say their “sinuses are acting up” really have allergies, not infections. Nasal polyps, growths that develop in the nose or sinuses, can cause bothersome congestion.
Finally, cancer as always can occur, in the Nose, Mouth, Throat, Tongue, or Larynx. This happens primarily to smokers.
For the Lungs, see The Lower Respiratory System.